1) Soundgarden in Memphis (90s). They were switched from headliner to opener (for Kid Rock) and they played everything double speed. With their backs to the audience. I was there for just Soundgarden since Kid Rock sucks balls, so initially I thought it was funny but hindsight was disappointed they didn't play as expected.
2) The Sword. Saw them before and they rocked, but seems the lead singer/guitar is in the middle of a drug battle and his level of performing has gone down hill.
3) The Black Keys. Was stoked to take my then fiancee (now wife) to this show in Cincinnati. Drummer was wasted, timing sucked bad. Then my car was towed. Hell of a night, finally got my car back around 2am.